Sedimentary Facies Model Research Articles

Application of 3D Geological Modeling Technology for Single Sand Body in Block S

Abstract The P oil layer is generally in a medium to high water cut period, with scattered macroscopic residual oil distribution. The reserves are mainly distributed in the microfacies of river sand bodies, and the main layer is severely flooded with water, resulting in ineffective circulation in some areas. Therefore, it is necessary to tackle the modeling technology within the layer and describe the remaining oil within the layer to meet the needs of tapping the potential of remaining oil during the high water cut period. This article takes the establishment of a three-dimensional geological model of a single sand body within the S block layer as an example. Based on the establishment of a fine structural model, the “plane and vertical dual control” modeling method is used. The implementation method is: controlling the range of sedimentary facies maps → using the top surface of the sand body as the top depth of the river channel → controlling the vertical shape of the river channel through the facies controlled sandstone contour map, thereby achieving the vertical shape of the river channel through the facies controlled sandstone contour map, and establishing a three-dimensional sedimentary facies model of a single sand body. Optimize the method for characterizing interlayers, achieve modeling of single sand body interlayers, and perform random simulation interpolation in phases to obtain attribute models. The use of a single sand body model within a layer can visually display the three-dimensional channel morphology and classify the identified connected bodies within the study area. The upscaling method of sedimentary facies models with irregular boundaries greatly reduces the number of model grids and provides a relatively refined geological model for numerical simulation.

A 3D Geological Modeling Method for Grain-size Lithofacies of Tight Sandstone Gas Reservoirs: A Case Study of Xujiahe Formation Gas Reservoir in Sichuan Basin, China

Tight sandstone gas reservoir has strong heterogeneity, and it is difficult to control the change of internal storage and permeability properties by simple sedimentary facies. It is necessary to explore a geological modeling method that can more accurately characterize the distribution of high-quality reservoirs. Taking the Xujiahe Formation gas reservoir in Xinchang area, Sichuan Basin, China as an example, this paper introduces the modeling method of three orders: sand-mudstone facies, sedimentary facies and grain-size lithofacies, so as to realize the spatial characterization of high-quality tight sandstone reservoirs with strong heterogeneity. In this technical process, the sand-mudstone model is first established. Based on the sand and mudstone model, four sedimentary types (or sedimentary facies) of distributary channel, channel edge, interdistributary bay and mouth bar are further divided. The sedimentary facies model is constructed by multi-point geostatistical modeling method. The quantitative relationship between sedimentary facies and grain-size lithofacies is linked by using argillaceous content as a “bridge”. The spatial distribution probability of grain-size lithofacies is constrained by the neural network clustering of argillaceous content and natural gamma-ray data in three-dimensional space. By controlling the types, ratios, and boundaries of grain-size lithofacies through sedimentary facies, and combining probabilistic bodies to cooperate with constraints, precise simulation of lithofacies can be achieved. The grain-size lithology lithofacies model established by this method follows the depositional law in space and has more reasonable contact relations between various sand bodies. The anastomosis rate of the model reached 85% with the new drilling test. This paper provides a new modeling idea for quantitative characterization and prediction of high-quality tight sandstone gas reservoirs, and provides a more accurate model basis.

Research on the Construction Method of a Training Image Library Based on cDCGAN

There is a close relationship between the size and property of a reservoir and the production and capacity. Therefore, in the process of oil and gas field exploration and development, it is of great importance to study the macro distribution of oil–gas reservoirs, the inner structure, the distribution of reservoir parameters, and the dynamic variation of reservoir characteristics. A reservoir model is an important bridge between first-hand geologic data and other results such as ground stress models and fracture models, and the quality of the model can influence the evaluation of the sweet spots, the deployment of a horizontal well, and the optimization of the well network. Reservoir facies modeling and physical parameter modeling are the key points in reservoir characterization and modeling. Deep learning, as an artificial intelligence method, has been shown to be a powerful tool in many fields, such as data fusion, feature extraction, pattern recognition, and nonlinear fitting. Thus, deep learning can be used to characterize the reservoir features in 3D space. In recent years, there have been increasing attempts to apply deep learning in the oil and gas industry, and many scholars have made attempts in logging interpretation, seismic processing and interpretation, geological modeling, and petroleum engineering. Traditional training image construction methods have drawbacks such as low construction efficiency and limited types of sedimentary facies. For this purpose, some of the problems of the current reservoir facies modeling are solved in this paper. This study constructs a method that can quickly generate multiple types of sedimentary facies training images based on deep learning. Based on the features and merits of all kinds of deep learning methods, this paper makes some improvements and optimizations to the conventional reservoir facies modeling. The main outcomes of this thesis are as follows: (a) the construction of a training image library for reservoir facies modeling is realized. (b) the concept model of the typical sedimentary facies domain is used as a key constraint in the training image library. In order to construct a conditional convolutional adversarial network model, One-Hot and Distributed Representation is used to label the dataset. (c) The method is verified and tested with typical sedimentary facies types such as fluvial and delta. The results show that this method can generate six kinds of non-homogeneous and homogeneous training images that are almost identical to the target sedimentary facies in terms of generation quality. In terms of generating result formats, compared to the cDCGAN training image generation method, traditional methods took 31.5 and 9 times longer. In terms of generating result formats, cDCGAN can generate more formats than traditional methods. Furthermore, the method can store and rapidly generate the training image library of the typical sedimentary facies model of various types and styles in terms of generation efficiency.

Multiple-Point Geostatistical Simulation of Nonstationary Sedimentary Facies Models Based on Fuzzy Rough Sets and Spatial-Feature Method

Summary 3D simulation of sedimentary facies using seismic data is vital for reservoir evaluation and estimation of oil and gas reserves. As a result of the high nonstationarity of sedimentary facies and the highly nonlinear characteristics of seismic attributes, the mapping relationship with sedimentary facies has certain ambiguities and uncertainties that affect the modeling results of sedimentary facies. Multipoint geostatistics (MPS) has proven to be an effective technique for modeling subsurface geological bodies. However, the conventional MPS only deals with stationary applications, and its capability of revealing the distribution of sedimentary facies is thereby limited. In addition, the task of seismic attributes selection, which significantly affects the performance of the modeling method in simulating the distribution of sedimentary facies, is difficult because the relationship between sedimentary facies and seismic attributes is complex. This article presents a nonstationary modeling method for simulating the distribution of sedimentary facies, which is featured by the multiscale spatial feature of patterns. In particular, the spatial location of the patterns is introduced as auxiliary information in the classification and simulation processes. The method incorporates multiscale results during the modeling procedure. Patterns from the multicategory training images (TIs) are classified by the optimized workflow. The seismic attribute selection is achieved by using fuzzy-rough sets. The proposed simulation method is verified by two typical TIs, followed by applications to predict the actual distribution of sedimentary facies. Compared with the filter-based pattern simulation (FILTERSIM) approach, the proposed simulation method is applicable for revealing detailed subsurface models, especially under complex geological conditions and limited information.

About this title - Ichnology in Shallow-marine and Transitional Environments

The ichnology of shallow-marine to transitional environments is a key field of study with respect to understanding the variability of environmental parameters from inshore marginal-marine settings to the offshore transition zone. Over the last decades ichnology has evolved from being a tool to determine bathymetry, becoming the standard palaeoenvironmental methodology by which trace fossils can be used to inform sedimentary facies models. In particular, the analysis of mixed assemblages of invertebrate and vertebrate trace fossils allows detailed palaeoenvironmental and facies analysis. This volume focuses on the ichnological record of shallow-marine to transitional environments through the geological record, in addition to modern ones through neoichnology.

Multi-condition controlled sedimentary facies modeling based on generative adversarial network

Obtaining reliable sedimentary facies models is critical for geology, which primarily involves inferring conditional distributions from sparse wells. Multiple-point simulation (MPS) captures complex geological patterns by simulating multi-point probabilities, but it is sensitive to the stationarity of training images, and the limited training image is difficult to reflect the uncertainty of the prior geological models. Generative Adversarial Networks (GANs) have recently been proposed to spontaneously simulate multiple geological models that behave differently, generating realizations that respect spatial observations (hard data), with impressive results. In this paper, we explore a more flexible approach to conditioning synthetic realizations beyond hard data, allowing stylistic control over the realizations. We construct a conditional generative adversarial network consisting of a deep generator and a multi-scale discriminator as the conditional mapping model, and obtained realizations with improved visual quality. Based on this, style codes, which are numerical codes representing geological properties, are introduced to extend the existing mapping model. The resulting extended generative model can synthesize images that respect the hard data and exhibit the desired geological style. In addition, we collect and construct a dataset, which contains abundant and realistic fluvial patterns to reflect adequate prior geological knowledge. Extensive experiments have been carried out on this dataset, the results show that the generated images reflect absolute responses to style codes while maintaining the matching rate of 94.78% to the hard data, which can provide new ideas for conditional geological modeling.

On the representability of soil water samples in space and time: Impact of heterogeneous solute transport pathways underneath a sandy field

In Europe, millions of water samples have been collected from sampling points, especially in the saturated zone to assess the water quality among others to fulfil EU water quality directives. Often water samples are collected from sampling points installed in the subsurface without knowing what the water collected represents in space and time. As such, without detailed knowledge of hydrogeological settings and fluctuations in groundwater levels, it is not possible to assess whether water collected represents a hydraulic active sediment setting or an adjacent isolated sediment body. Collecting water from the latter will hence not reveal by analysis potential contamination in the hydraulic active setting. Based on a detailed three-dimensional sedimentary facies model interpreted from geological and geophysical data combined with groundwater level measurements, this study focuses on delineating the impact of changing solute transport pathways underneath a sandy field (2 ha) exposed to bromide and pesticide applications. Hence, the analyses utilize detections in water samples of bromide, pesticides, and/or their degradation products collected through 19 years at 25 sampling points. A special focus is on the relatively high concentration, long-termed leaching of four degradation products (1,2,4-triazole, CGA108906, PPU, and desethyl-terbuthylazine) through the field. The results show that even for sand, knowledge of the hydrogeological setting and in-situ fate knowledge is imperative to assess the representability of water being sampled from both the variably-saturated and saturated zone of the soil-sediment system. Especially, the sub-horizontal layered sediments with numerous facies shifts facilitate horizontal solute transport, and fluctuations in the groundwater table seem to be decisive for, which solute transport pathways are dominating. Such detailed insights are crucial for accurately assessing sources of contaminants, leaching risk of contaminants through the variably-saturated zone, and improving monitoring procedures in the protection of the water resources and hereby the water quality of the future.

Nyexon Rock Avalanches: A Special Intrusion Restraint Mechanism, Tibet, China

The Nyexon Rock Avalanches in the southern Qinghai-Tibet Plateau is a huge scale earthquake-induced slope disaster in the Holocene, the accumulation area has distinct sedimentological characteristics, which is of great significance for studying the intrusion and restraint mechanism during long-distance transportation of large rock avalanches or debris avalanche. This long-distance transportation induced a series of landform types, such as ridges, hills, and ravines; they are widely distributed in all areas and extensively developed shear zones, jigsaw cracks, and other structures within the sedimentary structure. With the analysis of DEM data and geological survey, two main types of basement structures and their transition relationships are distinguished; they play an essential role in the restraining bottom during rock avalanches. In the sedimentary structure, the block facies and mixing facies occupy the main body of the deposition from the center to the distal area. Under the basement restriction, mixing facies are formed between the bottom of the sedimentary layer and the basement sedimentary structure; the shear band is mainly developed along with the mixing facies and basement facies, which is accompanied by basement liquefaction and rheology. A sedimentary facies model is established based on the sedimentary structure sequence of the Nyexon Rock Avalanches transportation. After analyzing the failure mechanism of the rock avalanches, it is believed that in the initial stage of failure, the rock avalanches is transformed into a particle flow that is similar to the debris avalanche, which is restrained by the basement structure and lateral bound; then, an accumulated obstacle highland is formed in the central area after deceleration, making the transportation of the main fluid to deflect quickly.

Preliminary analysis of sedimentary characteristics and facies model of M-II layer in Kazakhstan Oilfield A

The lithologic melange accumulation of areskum formation in akshabluk area is one of the key strata in exploration. Its basement inheritance controls the whole process of Jurassic sedimentation, and the filling and leveling gradually reduces the terrain elevation difference; After the late Jurassic deformation, the flat paleogeomorphology was changed and the deposition of Early Cretaceous strata was controlled. Under the control of marker beds, sedimentary cycles are divided according to the cycle characteristics of logging curves. Under the control of cycle interface (standard layer), according to the cyclicity of logging curve (GR), combined with core and seismic data, it is divided step by step according to the cycle level, from large to small, that is, it is divided step by step according to “oil bearing series → oil reservoir group → small layer → sedimentary unit”, and a layered system is established. Vertically, M-I and M-II groups are developed from bottom to top. M-II group is divided into m-ii-1 and m-ii-2. M - II - 1 is subdivided into four sub layers: m - Ⅱ - 1A, M - II - 1B, M - II - 1c and M - II - 1D. Based on the comprehensive analysis of sedimentary background and paleostructural characteristics, according to the sedimentary location and sedimentary environment of oilfield a, and referring to core data and seismic data, it is determined that oilfield a develops three sedimentary facies: alluvial fan facies, fluvial facies and lacustrine facies. According to the seismic attribute slice and logging data, predict the sandstone thickness contour map of each sedimentary unit, divide the single well logging facies, study and divide the sedimentary subfacies and sedimentary microfacies according to the sedimentary model.

Ediacaran cap dolomite of Shennongjia, northern Yangtze Craton, South China

Ediacaran cap dolomites are strong evidence for the glaciation during the Neoproterozoic. Stratigraphic-sedimentological studies combined with δ13C and δ18O isotope analyses are used for defining the processes of post-glacier environmental changes and sea-level rise caused by glacier melting and the reconstruction of the depositional environments for the Doushantuo cap dolomites in Shennongjia, northern Yangtze Craton (YC). Like many other cap dolomites in the YC and worldwide, those in Shennongjia exhibit strongly negative δ13Ccarb excursions, ranging from −7.3 to −2.5 ‰ (averagely from −5.4 to −4.1 ‰). A laminated clast-free calcareous siltstone commonly occurs between the cap dolomite and the underlying diamictites, indicating a low-energy, shallow-water depositional environment, wherein alkaline conditions developed before the deposition of the cap dolomite. The most prominent features of the cap dolomites in Shennongjia are the very thin thickness and monotonous sedimentary structures. The maximum thickness of the cap dolomites from the six sections in Shennongjia is 1.8 m, and the thinnest cap dolomite is 0.4 m with simple laminations. Sedimentary structures such as low-angle cross-bedding, giant wave ripples, sheet-crack cement, and tepee breccias are rare in Shennongjia except in the area near the Three Gorges. These evidences, therefore, point to the deposition of the Shennongjia cap dolomite in restricted shallow-water tidal environments.The space–time distribution of sedimentary facies in Shennongjia and the southeastern areas to Shennongjia indicate that the Ediacaran cap dolomite was formed on a ramp. Accordingly, we propose a sedimentary facies model for the formation of the cap dolomite, covering the inner and middle ramp facies. This model explains the thickness variations and distributions of the cap dolomites at both the local and regional scale, including their sedimentary structures, compositions, and barite occurrences. The model successfully illustrates why the cap dolomites in the Shennongjia area share a unique set of sedimentary features. Finally, the cap dolomite is interpreted as a diachronous deposit (bottom to top), tracking glacioeustatic flooding and recording ocean-wide changes over the time following deglaciation, and a correlation and cause of negative δ13Ccarb excursions in cap dolomites worldwide, particularly in those in the Yangtze Carton, are further discussed.

Channel Migration of the Meandering River Fan: A Case Study of the Okavango Delta

Okavango delta is a typical distributive fluvial system, which is composed of a series of sand island-river-swamp networks. River migration in the Okavango delta is analyzed by using satellite images from Google Earth and Alaska Satellite Facility (ASF). Four configuration characterization parameters are selected to depict and measure the meandering river. These four parameters are sinuosity index (S), curvature (C), the difference of along-current deflection angle (Δθ) and expansion coefficient (Km). In the fan, the channel migration is mainly asymmetric. According to geomorphic elements and associated features, Okavango Delta can be subdivided into three zones: axial zone, median zone and distal zone. Under the influence of slope, climate and vegetation, different migration modes are developed in different zones. As the river moves downstream, the sinuosity index of the river on the Okavango Delta decreases downstream. Based on the characteristics of different zones, the sedimentary facies model of a single source distributive fluvial system of a meandering river is proposed. The models of channel migration and sedimentary facies have wide application. This research will not only provide a basis for the prediction of future river channels but will also provide important theoretical guidance for the study of the sedimentary morphology of underground reservoirs.

Research on Sedimentary Microfacies of an Oil Layer in a Block of Songliao Basin

This topic uses debris, core log, core description data, combines regional research results, determine that the oil layer in a block of the Songliao Basin is the most developed in the front subfacies and prodelta subfacies of delta underwater sediment. Microfacies include underwater distributary channels, underwater natural levees, distributary bays, estuary dams, distal bars, sheet sand, and prodelta mud. The contiguous distribution of dam sand is the main feature of this area. On the basis of single-well facies research, it is the first time that this topic has studied the features of the plane and profile distribution of the reservoir sedimentary facies belt in the study area, and finally builds the sedimentary facies model, and provides a solid geological basis for fine reservoir description and favorable area prediction.

Sedimentary facies of a tide-dominated estuary and deltaic complex in a tropical setting: The middle Miocene Oficina Formation of the Orinoco Oil Belt, Venezuela

Although the middle Miocene Oficina Formation of the Orinoco Oil Belt represents most of Venezuela's hydrocarbon resource, a comprehensive and detailed sedimentary facies model for the whole belt has never been put forward. Based on the analysis of cores and well logs, nine sedimentary facies (FA-I), forming five facies assemblages (FA1-5), have been characterized. Both sedimentologic and ichnologic datasets have been integrated in this study. The Oficina Formation records the typical succession of fluvial incision during relative sea-level fall, fluvial deposition during lowstand, transition from fluvial to estuary valleys during the subsequent transgression and deltaic progradation during highstand. FA1 consists of fluvial-braided channel (FB), floodplain (FG2), and swamp (FH1) deposits, as well as paleosols (FG3). This facies assemblage occurs in the lower member, representing the infill of lowstand fluvial valleys. FA2 consists of meandering estuary-channel deposits (FA, FC, FD, FE, and FI). This facies assemblage occurs in the middle member, representing the infill of tide-dominated estuary valleys during the early stages of the Langhian transgression. FA3 consists of tidal-flat and tidal-creek (FC, FD, FE, FF, and FG2), and swamp (FH1 and FH2) deposits, together with paleosols (FG3). This facies assemblage is present in the middle member, revealing backstepping and retrogradation within the estuary system during a continuing transgression. FA4 consists of outer-estuary sandbar (FC, FD, and FG1); swamp (FH2) deposits and paleosols are present at the margins of the estuary (FG3). This facies assemblage occurs in the uppermost part of the middle members, representing a late stage of the Langhian transgression, culminating in a maximum flooding surface. FA5 consists of deltaic distributary channel (FC and FD), floodplain and interdistributary-bay (FG2), and swamp (FH1) deposits. This facies assemblage occurs in the upper member, recording sedimentation in the delta plain of a tide-dominated delta during a highstand. Freshwater conditions in the fluvial system, as well as in the inner portions of the estuary and the delta plain are further supported by the presence of the Scoyenia Ichnofacies, whereas brackish-water segments of the estuary are characterized by the Skolithos and depauperate Cruziana Ichnofacies. The substrate-controlled Teredolites, and Glossifungites Ichnofacies occur in connection to erosional exhumation during ravinement. The absence of fully marine ichnofaunas is consistent with the embayed nature of the Orinoco Oil Belt. The tropical and humid character of the Oficina depositional systems is manifested in the development of widespread wetlands in marginal-marine settings, with formation of swamps and embayed areas, typically displaying evidence of waterlogged paleosols with pervasive root trace fossils. The abundance of crustacean burrows, such as Ophiomorpha and Thalassinoides, is also typical of low-latitude marginal- and shallow-marine settings. Although tidal forces tend to be weaker in lower latitudes because Coriolis effects are stronger there, both the estuary and delta systems are regarded as tide-dominated, most likely reflecting the embayed nature of the shoreline.

Effect of volcanic activities on the characteristic of sedimentary and sedimentary facies model-- Taking the Jiangbasitao Formation in Wulungu area as example

At present, the northern margin of Junggar Basin is one of the key zone in oil-gas exploration fields. For the purpose of explaining the question about the effect of volcanic activities on the characteristic of sedimentary, with the Wulungu area in the northern margin of Junggar Basin, the sedimentary characteristics was studied comprehensively using methods of core, drilling and a large number of sedimentologic experiment. The results have confirmed that the types of sedimentary facies, mainly marine. Combining with the construction environment, the sedimentary facies model (inter-arc basin and back-arc basin) were established for this area.

Facies and stratigraphic associations of Sinjar and Khurmala Formation, Dohuk Area, Kurdistan Region, Iraq

The carbonate facies of the Lower Eocene Sinjar and Khurmala Formations are stratigraphically interrelated and forms part of the shoaling stage sediments of the Zagros Foreland Basin. This work aims at investigating their stratigraphic associations at Dohuk area of NE Iraq. Both Formations are well exposed in three sections examined from Dohuk area including Spindar (Gara Mt.), Birkyat (Khair Mt.) for Khurmala Formation, and Barbuhar (Bekhair Mt.) for Sinjar Formation. The thickness of the Khurmala Formation varies from 90.7 m at Spindar and 81 m at Birkyat. The thickness of the Sinjar Formation is 36.5 m at Barbuhar section. The focus of this study is to determine the carbonate microfacies in order to construct their sedimentary facies model and to interpret the depositional environment. Lithologically, Khurmala Formation in Spindar and Birkyat sections is closely similar and consisting of buff to gray, medium to thick, well-bedded microbialites dolostone, alternating with thin beds of soft shale and marlstone interlayer. The Barbuhar section consists mainly of three reefal limestone horizons alternating with siliciclastic interlayers. Four intensively dolomitized microfacies were recorded from Khurmala Formaton sections. These are dolo-mudstone, microbial dolo-mudstone, foraminiferal algal dolo-packstone, and foraminiferal dolo-wackestone, whereas Sinjar Formation shows eight carbonate microfacies, which are coraline framestone, bioclastic coralgal rudstone, coralgal foraminiferal bioclastic packstone, foraminifera bioclastic algal packstone, bioclastic forminiferal packstone, dolomitic microbial bindstone, dolomitic microbial laminite, and bioclastic sandy limestone. Field observations, along with microscopic investigations, have resulted in identifying facies types of the two formations. The Khurmala Formation in Spindar and Birkyat seems to be deposited in a shallow shelf setting of supratidal, intertidal, and semi-restricted lagoonal facies with siliciclastic-dominated coastal plain. The section of Barbuhar represents the Sinjar Formation which is deposited at further seaward position of the shelf as a patch reef limestone which is intermixed with the Kolosh Formation sandstone in a further deeper position.

Multi-Point Geostatistical Sedimentary Facies Modeling Based on Three-Dimensional Training Images

As an important modeling parameter in multi-point geostatistics, training images determine the modeling effect to a great extent. It is necessary to evaluate and optimize the applicability of candidate training images before modeling by multi-point geostatistics. Conventional two-dimensional training images can’t describe the overlapping relation of sedimentary facies in space, and there is a deficiency in describing the event relation of single data. This paper puts forward a new training image optimization method. The basic idea is to arrange and analyze sand bodies filled with sedimentary sand bodies in point dams and river channels in different periods. The method of obtaining three-dimensional training images is to use sand thickness maps and sedimentary facies maps for spatial constraints. The simulation test shows that compared with the sedimentary facies model obtained from two-dimensional training images, the sedimentary facies model obtained from three-dimensional training images through multi-point geostatistics has high compatibility and is more in line with geological understanding. On the basis of fully understanding the development characteristics of the sedimentary system and quantitative geometry of sedimentary body in the study area, sedimentary microfacies models based on sequential indicator simulation method and target simulation method are established, respectively. By comparing and analyzing the sedimentary microfacies models established by three different methods, the results show that the multi-point geostatistics can stably present the planar distribution characteristics and overlapping spatial relationship of sedimentary microfacies and reproduce the complex spatial structure and geometric shape of fluvial facies. The model established by this method is more in line with the geological sedimentary model.

Contourites and bottom current reworked sands: Bed facies model and implications

The differentiation of pure turbidites and contourites from mixed deposits —as the bottom current reworked sands (BCRS) — in sedimentary cores and outcrops from the modern or ancient records is still challenging. An accurate evaluation of facies associations calls for detailed understanding of processes controlling these deep-water systems and how they record interactions of along- and down-slope processes. Connecting features to processes is of particularly relevant in the study of contouritic drifts that include sandy deposits. This research describes and interprets BCRS within a Pleistocene contouritic drift located along the middle continental slope of the Gulf of Cadiz. Seismic, wireline, and sedimentological analyses of sediment samples were applied to core material representing a muddy drift that hosts sandy deposits. A sedimentary sequence, comprising five facies (F1 to F5) is defined here; it records background sedimentation influenced by the initial deposition of a gravity-driven flow followed by bottom current reworking. It is moderately bioturbated and contains distinctive trace fossil assemblages, often dominated by ichnofabrics of the Planolites and Thalassinoides. These assemblages represent intermittent deposition between down-slope and along-slope processes during relatively short time scales. The sequence is defined as a partial bi-gradational contourite sequence including BCRS reworked from underlying turbiditic deposits due to the interaction of down- and along- slope processes within the contouritic drift and its adjacent contouritic channel. Longer-term trends include an increase and subsequent decrease in both sediment supply and bottom currents. The sedimentary facies model presented here represents a new end member for a mixed turbiditic-contouritic system in which turbiditic flows influence a contourite drift. As such, it may support basic sedimentological interpretation and petroleum exploration strategies.

Stratigraphy and sedimentology of distal-alluvial and lacustrine deposits of the western-central Ebro Basin (NE Iberia) reflecting the onset of the middle Miocene Climatic Optimum

Stratigraphic and sedimentological study of distal alluvial and lacustrine deposits in the Plana de la Negra-Sancho Abarca area (western-central Ebro Basin, NE Iberia) within the early and middle Miocene allows five main lithofacies to be characterized and mapped within two tectosedimentary units, construction of a sedimentary facies model and discussion on allogenic controls on sedimentation. In this area, the boundary between tectosedimentary units T5 and T6 appears to be conformable and is marked by the change from dominant clastics to carbonates. Correlation of the studied outcrops with nearby sections that already had magnetostratigraphic and biostratigraphic data allows the studied succession to be dated from C5Dr to C5Cn (Burdigalian-Langhian), placing the boundary T5/T6 at ca. 16.1-16.05Ma. Seven vertical facies sequences document deposition of distal alluvial clastics and palustrine and lacustrine carbonates. Sandstones and mudstones represent low-sinuosity channels and lateral and terminal splays by unconfined flows runnig across the alluvial plain, associated to the Pyrenean-derived Luna fluvial system. The carbonates contain charophytes, ostracods, bivalves and gastropods, indicating deposition in 2-4m deep lakes. Laminated carbonate facies record reworking of shore carbonates and the influx fine-siliciclastic sediment offshore. Abundant bioturbation and desiccation features indicate episodic submergence and subaerial exposure. Four main episodes of alluvial and associated palustrine/lacustrine facies belt shifts are identified. Alluvial deposition in the studied T5 unit is related to low lake level conditions, rather than to a Pyrenean uplift. The maximum extent of the freshwater carbonates occur at the base of unit T6. This is consistent with conditions of increasing humidity of the Middle Miocene Climatic Optimum.

Adaptability of Combined Well Pattern to Sedimentary Facies Model in Thin Interbedded, Extra-Low Permeability Reservoirs

Adaptability of Combined Well Pattern to Sedimentary Facies Model in Thin Interbedded, Extra-Low Permeability Reservoirs

Application of 3D Reservoir Geological Model on Es1 Formation, Block Nv32, Shenvsi Oilfield, China

Three-dimensional geological modeling of reservoirs is an essential tool to predict reservoir performance and improve the understanding of reservoir uniqueness in Es1 formation. The paper focuses on the use of petrel software to build three-dimensional reservoir geological model which characterizes and assesses block Nv32 that located in the west of the Shenvsi oilfield in the south of Cangzhou city, Hebei province of China, and has an oil-bearing area of 1.4 km2. This study is depending on integration data from well logs of 22 wells which provided from geology, geophysics, and petrophysics to identify and provide precise depict of the subsurface internal structure and the reservoir heterogeneity. Input data was used to build the structural model, sedimentary facies model, petrophysical properties (porosity, permeability, saturation, and N/G model, and finally to determine the reservoir volume. The lithological facies were simulated using the assigned value method. Moreover, Petrophysical properties (Porosity, permeability, oil saturation and net to gross) were constructed for each zone using the Sequential Gaussian Simulation method to guide the distribution of petrophysical properties of Es1 formation, block Nv32. Statistical analysis of the porosity, permeability, oil saturation and N/G model present that the porosity occurrence distribution is mainly concern between 0.2% - 36.39% of block Nv32 with an average porosity value of 17.5%, permeability between 0.017 mD to 974.8 mD, having an average permeability of 59.44 mD, oil saturation between 0.00 to 0.95 having an average value of 0.22, and N/G is mainly concentrated between 0.01 to 1.00 within an average value of 0.61. This research has indicated the reliability of the three-dimensional model technique as a suitable tool to provide a sufficient understanding of petrophysical distribution. The south-western and north-western indicate that oilfield is very promising an exploratory well should be drilled to find out the thickness and size of the reservoir.